As Northwestern’s chief maintenance engineer, Vandas knows these pipes and tunnels well. They are part of a complex system that carries steam and chilled water from the Central Utility Plant to heat and cool more than 200 buildings on the Evanston campus. Vandas and his team are responsible for keeping this system running safely and efficiently. Since 2013, they have made adjustments that cut energy costs by $2 million dollars annually and improved the safety of the system. It’s all thanks to the repair and maintenance of inconspicuous yet vital components: steam traps.
Immediate Financial Paybacks
“The cheapest and least environmentally impactful energy is that which is not used,” said John D’Angelo, vice president for Northwestern Facilities Management (NUFM). “Changing filters, repairing steam traps and maintaining weather barriers on doors all have immediate financial paybacks and reduce our energy use.” Northwestern uses more than 1 billion pounds of steam annually to heat buildings and water, to run kitchen equipment and more. At the Central Utility Plant, situated in the center of campus near Lake Michigan, water is heated until it becomes steam. High-pressure steam is then piped through an elaborate underground system of tunnels that provides energy for campus residences, offices, dining halls and classrooms.
Tackling Energy Use in the Built Environment
The intricate infrastructure that powers Northwestern’s many facilities-its built environment-accounts for the vast majority of the University’s energy use, D’Angelo said. And energy use represents 80 percent of Northwestern’s carbon footprint, making the built environment ripe for energy-saving solutions to reach the University’s commitment to achieve net-zero emissions by 2050.
“For the past couple of years, we’ve really focused on low-hanging fruit projects,” said Kathia Benitez, Northwestern’s director of sustainability. “Once we have a greater understanding of our energy use at the individual building level, these smaller projects eventually will turn into bigger projects that will allow us to take a proactive approach rather than a reactive approach to energy management.”
That’s where projects like the campus-wide overhaul of all 1,851 steam traps come in to play. While the University continues to assess its energy usage building by building through a formal energy audit, NUFM is already taking several steps to reach Northwestern’s commitment to reduce energy consumption 20 percent from 2010 levels by 2020.
Switching to Energy-Efficient Exterior Lighting
For example, NUFM recently switched all exterior lighting (outdoors on campus) to energy efficient LEDs. Soon “EXIT” signs in the University’s buildings will follow suit. The University and sustainNU (Northwestern’s Office of Sustainability) has been a partner of the Environmental Protection Agency’s ENERGY STAR program since 2015, following the program’s guidelines for energy management and tracking, while also benchmarking University energy, water and waste performance via the program’s Portfolio Manager software. The University also is enrolled in the Department of Energy’s Better Buildings Initiative.
How Steam Traps Work
When steam traps malfunction, energy is wasted, heat transfers are less efficient and conditions can become dangerous. As steam radiates heat, it slowly cools and condenses back into water, called condensate. If condensate isn’t removed from the pipes, it can pool up and block steam from traveling into buildings, reducing the efficiency of the system and creating a hazard. The fast-moving, high-pressure steam can pick up water droplets from the condensate and form a projectile called a water hammer- which, when accelerated, can slam hard enough to burst through steel pipes and valves. The steam distribution system uses steam traps to manage that hazard.
A steam trap is an automatic valve that filters out condensate as it collects in pipes. When enough condensate builds up, the trap opens and releases it into other pipes that make up the condensate return system, which sends the water back to the main collection tank to again be converted into steam at the boiler.
Ramping Up Energy Efficiency Efforts
Annual steam trap surveys began in 2013, when Northwestern started ramping up its energy efficiency efforts. The first survey found that 23 percent of steam traps on the Evanston campus were failing, causing leaks of more than 100 million pounds of steam-the equivalent to the annual energy use of 800 average homes. Each year, NUFM staff spend eight hours a day for three weeks checking every steam trap to ensure they are functioning properly. “We replaced or repaired as many of the leaks as we could after that survey,” Vandas said. “Since then, things are much better, and have stayed that way.”
The change was drastic. By 2015, less than 4 percent of steam traps were failing. This year, steam traps are functioning at similar rates, and, all told, steam trap work has resulted in a 90 percent decrease in wasted energy since 2013 and savings of almost $2 million per year. NUFM and its partners plan to continue building on recent successes, transforming the University into a 100 percent sustainable operation. “Our vision is to improve the builtenvironment at Northwestern so that we lessen our harm to the environment and reduce greenhouse gas emissions,” Benitez said. “There’s a lot of work ahead of us, and the built environment is among the many things that we’ll be looking at.”